Pyrolysis and Gasification – State of the Art

Considering the worldwide number of installations as well as their capacity, the most dominating treatment method for waste is incineration. Currently, 225 million tons of waste are treated in 2,200 facilities.

Besides this established and – concerning oxygen input
– overall hyperstoichiometric treatment method (excess air conditions), the
substoichiometric processes pyrolysis and gasification are also found in the
market. These so-called alternative methods have been presented by different
providers under varying names ever since the 1970ies. Their characteristic lies
in comparably complex systems engineering and process equipment. According to
suppliers, the advantage of substoichiometric processes lies in higher electrical
efficiency and/or a higher quality of conversion products, for example
vitrified slag of low leachability or non-fossil liquid fuels.

While
alternative processes have gained no relevance in Germany due to experiences marked
by setbacks, discussion abroad has intensified in recent times and some lobby groups
and decision makers explicitly claim the use of these technologies for waste treatment.
Supporters point out successful long-time operation of facilities in Asia, especially
in Japan. Yet it must be considered that the general framework and waste
treatment policy in this region differs significantly from that in Europe or
North America.

Practical experiences mentioned above mainly refer to
gasification and pyrolysis plants. Besides these classic thermochemical
processes, other alternative processes have entered the market in the last few
years.